cat /dev/dsp does sample the ADC
It's then 'simply' a case of setting the mixer controls so that the sound is routed from the mic to the adc
See the nice simple explanatory block diagram in the middle of http://wiki.openmoko.org/wiki/Neo1973_Audio_Subsystem for guidance.
In principle. You need to find which mic input the mic is connected to, setup the input gain and mic selector appropriately,setup the ALC mixer right, then set it up to route to the left or right ADC
alsactl can do it (alsamixer)

cat /dev/dsp does sample the ADC
It's then 'simply' a case of setting the mixer controls so that the sound is routed from the mic to the adc
See the nice simple explanatory block diagram in the middle of http://wiki.openmoko.org/wiki/Neo1973_Audio_Subsystem for guidance.
In principle. You need to find which mic input the mic is connected to, setup the input gain and mic selector appropriately,setup the ALC mixer right, then set it up to route to the left or right ADC
alsactl can do it (alsamixer)